Wataru Kitamura, the owner of a small computer security company, has taken the same train to work every morning for 28 years.

He is a youthful-looking 69-year-old with a certain dignity in his bearing which makes him stand out among the crowd of commuters; a corporate foot-soldier in Japan's economy who relies on Tokyo's huge railway network to get him to the office on time.

Well-built and well-staffed, the train system operates with precision and efficiency matched in few other countries, and feels completely safe.

Suddenly I realised my nose and eyes were running, and I was feeling so strange - that was when I decided to go to hospital

Wataru Kitamura

Which is why what happened to Mr Kitamura and thousands of other commuters nine years ago came as such a shock. On 20 March, 1995, while travelling the same route to work, he was caught up in the first ever terrorist attack with chemical weapons.

"That day I got out at Kasumigaseki station as usual to change trains," he recalled.

"There were long delays, which was unusual. I had to wait 40 minutes, but eventually made it to the office. On the way I noticed lots of ambulances racing past. When I arrived, my secretary pointed to the television, and I could see all the injured people lying outside Kasumigaseki.

"Suddenly I realised my nose and eyes were running, and I was feeling so strange. That was when I decided to go to hospital," he said.

At the time nobody realised that members of the Aum Shinrikyo cult had punctured bags of the deadly nerve gas sarin on five trains.

Commuters started to feel short of breath, and then experienced dim vision. Some collapsed. At Kasumigaseki two railway officials died trying to dispose of the contaminated bags. At the entrances of several stations people lay on the pavement, coughing and vomiting, waiting for ambulances to reach them.

The attack killed 12 and made about 5,000 ill

Twelve people died, and about 5,000 were injured. Mr Kitamura's symptoms were comparatively mild, but even today he suffers severe colds and aches from the gas.

The Aum cult has since re-named itself Aleph, the first letter of the Hebrew alphabet. Its devotees still follow a bizarre set of beliefs, blending Tibetan Buddhism, Hinduism and the thoughts of the movement's founder and guru, Shoko Asahara, who on Friday was sentenced to death for masterminding the attack.

They live a simple communal life in several locations across Japan. Membership has dropped from an estimated 10,000 in 1995, to several hundred - still mainly alienated young people seeking a spiritual retreat from the material values of modern Japan. They shun the world, and are shunned by it.

One of their bases is in the suburb of Setagaya, west of Tokyo. Police guard both entrances of the narrow street, and make careful note of everyone who enters or leaves. Banners demanding the sect leave hang from the balconies of neighbouring apartments.

Aum is still attracting devotees

A nervous-looking young man came down the staircase of a shabby apartment block and introduced himself as an Aleph spokesman, Noboyuki Matsuo.

He spoke good English - he said he spent his early childhood in San Francisco. He said that he was sorry but, because of the intense media pressure, there would not be any interviews for the moment. But he did take pains to explain that the cult has changed.

"What happened in 1995 was a terrible crime, and we will keep on apologising for it," he said.

But asked whether the group had severed all ties with Asahara, he replied: "He is still our guru, even if he was responsible for those attacks."

Mr Matsuo seemed polite and very sincere. He would not say exactly how long he had been in the cult, but he said it was longer than 10 years.

I think even I could have done such a thing if I'd been ordered to

Former Aum member Tatsuya Nagaoka on the sarin attacks

At a Shinto temple north of Tokyo I met Tatsuya Nagaoka, who was a member of Aum for two years before leaving in 1990. He, too, comes across as a thoughtful, slightly unworldly man.

"The thing I liked about Aum was it gave me very clear answers, unlike other religions. For instance, if I had a problem, there were always exercises like meditation designed to help sort it out in my mind," he explained.

I asked whether, back then, he had any idea Aum members would carry out something like the sarin gas attacks.

"Actually I wasn't that surprised, because the word of the guru, Asahara, was absolute, and everyone had to follow his orders. I think even I could have done such a thing if I'd been ordered to," he said.

Even now, 14 years after his father helped him escape from Aum, and as a husband and father of two children, he is having difficulty adjusting. He works only occasionally, relying on his wife's income, and dabbles in Tibetan Buddhism.

He rejects the way Asahara led Aum, and the terrible things it did. But he is still searching for something to fill the spiritual void he feels in life outside the cult.